Conventionally, there is known a system to inspect an optical cable which is laid between two points. For example, Japanese Unexamined Patent Publication No. H10-336106 and Japanese Unexamined Patent Publication No. 2000-295185 disclose a measurement device for inspecting an optical fiber by an OTDR (Optical Time Domain Reflectometer) method of emitting an optical pulse to one end of the optical fiber to measure a light returning to the one end by backward scattering and reflecting.